A University of Maine researcher has found evidence that many teenaged girls are not getting enough vitamin D, either from their diets or sun exposure. Lack of the critical nutrient could lead to health risks later in life, especially for osteoporosis.

Susan Sullivan, a clinical dietitian, monitored sun exposure, diet and blood levels of vitamin D in 23 girls aged 10 to 13 years from the Bangor, Maine area. She found that almost half of the girls in her study had insufficient levels of vitamin D in their blood in March, a time of the year when the nutrient usually falls to its lowest level. In September, when the nutrient is usually at its highest level, 17% also fell below the standard.

“We’ve known for a long time that vitamin D has a role in getting calcium into bones. Researchers are now finding evidence that vitamin D could play other roles in health such as cancer prevention and controlling blood pressure. There are vitamin D receptors in lots of tissues in the body that aren’t related to bone,” she explains.

The largest single source of vitamin D is the skin, which makes the nutrient when it is exposed to sunlight. Diet plays a less important role but, for people at high northern latitudes, it helps to supplement the body’s vitamin D store during the winter months when sunlight is less intense.

To generate vitamin D, Sullivan and other nutritionists recommend getting 5 to 10 minutes of sun exposure between roughly 10 am and 2 pm daily in the summer. Vitamin D-fortified foods or supplements are helpful. Fatty fish such as salmon also provide a vitamin D boost.

University of Maine, Jan 29, 2004